1. Field
The present invention relates generally to communications, and more specifically to a novel and improved method and apparatus for W-CDMA modulation.
2. Background
Wireless communication systems are widely deployed to provide various types of communication such as voice, data, and so on. These systems may be based on code division multiple access (CDMA), time division multiple access (TDMA), or some other modulation techniques. A CDMA system provides certain advantages over other types of systems, including increased system capacity.
A CDMA system may be designed to support one or more CDMA standards such as (1) the “TIA/EIA-95-B Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System” (the IS-95 standard), (2) the “TIA/EIA-98-C Recommended Minimum Standard for Dual-Mode Wideband Spread Spectrum Cellular Mobile Station” (the IS-98 standard), (3) the standard offered by a consortium named “3rd Generation Partnership Project” (3GPP) and embodied in a set of documents including Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214 (the W-CDMA standard), (4) the standard offered by a consortium named “3rd Generation Partnership Project 2” (3GPP2) and embodied in a set of documents including “TR-45.5 Physical Layer Standard for cdma2000 Spread Spectrum Systems,” the “C.S0005-A Upper Layer (Layer 3) Signaling Standard for cdma2000 Spread Spectrum Systems,” and the “C.S0024 cdma2000 High Rate Packet Data Air Interface Specification” (the cdma2000 standard), and (5) some other standards. A system that implements the High Rate Packet Data specification of the cdma2000 standard is referred to herein as a high data rate (HDR) system. The HDR system is documented in TIA/EIA-IS-856, “CDMA2000 High Rate Packet Data Air Interface Specification”. Proposed wireless systems also provide a combination of HDR and low data rate services (such as voice and fax services) using a single air interface.
Modern CDMA system specifications, such as those referenced above, incorporate a variety of requirements and prescribe various signaling schemes in order to achieve the advantages attributed to them. As additional requirements and signaling schemes grow, so does the complexity and quantity of resources needed to support them. However, in a mobile wireless environment, it is desirable to minimize hardware and current consumption, in an effort to produce user equipment that is cost-effective and power-efficient in a compact form factor.
Modulators and demodulators are commonly deployed in wireless communication systems. Modulators format and process various kinds of data, such as voice, video, internet, or other data, using various techniques to prepare it for transmission. These techniques include CRC generation, ciphering, channel coding, interleaving, rate matching, channelization, scrambling, etc. Demodulators are designed to extract the data from the formatted transmission after it is received. The W-CDMA standard provides requirements and delineates certain processing techniques for modulation of data according to that standard. The W-CDMA standard is no less complex than its predecessors, and the desire for cost-effective and power-efficient devices within W-CDMA systems is ever present.
As such, there is a need in the art for modulators that effectively implement the requirements of complex standards while minimizing associated hardware costs, power consumption, and complexity of system design.